The present invention is drawn to novel antiviral compounds, pharmaceutical compositions and their use. More specifically this invention is drawn to derivatives of monocyclic polyamines which have activity in standard tests against HIV-infected cells as well as other biological activity related to binding of ligands to chemokine receptors that mediate a number of mammalian embryonic developmental processes.
Approximately 40 human chemokines have been described, that function, at least in part, by modulating a complex and overlapping set of biological activities important for the movement of lymphoid cells and extravasation and tissue infiltration of leukocytes in response to inciting agents (See, for example: P. Ponath, Exp. Opin. Invest. Drugs, 7:1-18, 1998). These chemotactic cytokines, or chemokines, constitute a family of proteins, approximately 8-10 kDa in size. Chemokines appear to share a common structural motif, that consists of 4 conserved cysteines involved in maintaining tertiary structure. There are two major subfamilies of chemokines: the xe2x80x9cCCxe2x80x9d or xcex2-chemokines and the xe2x80x9cCXCxe2x80x9d or xcex1-chemokines. The receptors of these chemokines are classified based upon the chemokine that constitutes the receptor""s natural ligand. Receptors of the xcex2-chemokines are designated xe2x80x9cCCRxe2x80x9d; while those of the xcex1-chemokines are designated xe2x80x9cCXCRxe2x80x9d.
Chemokines are considered to be principal mediators in the initiation and maintenance of inflammation. More specifically, chemokines have been found to play an important role in the regulation of endothelial cell function, including proliferation, migration and differentiation during angiogenesis and re-endothelialization after injury (Gupta et al., J. Biolog. Chem., 7:4282-4287, 1998). Two specific chemokines have been implicated in the etiology of infection by human immunodeficiency virus (HIV).
In most instances, HIV initially binds via its gp120 envelope protein to the CD4 receptor of the target cell. A conformational change appears to take place in the gp120 which results in its subsequent binding to a chemokine receptor, such as CCR-5 (Wyatt et al., Science, 280:1884-1888 (1998)). HIV-1 isolates arising subsequently in the infection bind to the CXCR-4 chemokine receptor. In view of the fact that the feline immunodeficiency virus, another related retrovirus, binds to a chemokine receptor without needing to bind first to the CD4 receptor, suggests that chemokine receptors may be the primordial obligate receptors for immunodeficiency retroviruses.
Following the initial binding by HIV to CD4, virus-cell fusion results, which is mediated by members of the chemokine receptor family, with different members serving as fusion cofactors for macrophage-tropic (M-tropic) and T cell line-tropic (T-tropic) isolates of HIV-1 (Carroll et al., Science, 276: 273-276 1997). During the course of infection within a patient, it appears that a majority of HIV particles shift from the M-tropic to the more aggressive T-tropic viral phenotype (Miedema et al., Immune. Rev., 140:35 (1994)). Curiously, the M-tropic viral phenotype correlates with the virus""s ability to enter the cell following binding of the CCR-5 receptor, while the T-tropic viral phenotype correlates with viral entry into the cell following binding and membrane fusion with the CXCR-4 receptor. Clinically observations suggest that patients who possess genetic mutations in the CCR-5 or CXCR-4 appear resistant or less susceptible to HIV infection.
However, the binding of chemokine receptors to their natural ligands appears to serve a more evolutionary and central role than only as mediators of HIV infection. The chemokine receptor, CXCR-4 has been found to be essential for the vascularization of the gastrointestinal tract (Tachibana et al., Nature, 393:591-594 (1998)) as well as haematopoiesis and cerebellar development (Zou et al., Nature, 393:591-594 (1998)). Interference with any of these important functions served by the binding of pre-B-cell growth-stimulating factor/stromal derived factor (PBSF/SDF-1) to the CXCR-4 chemokine receptor results in lethal deficiencies in vascular development, haematopoiesis and cardiogenesis. Similarly, fetal cerebellar development appears to rely upon the effective functioning of CXCR-4 in neuronal cell migration and patterning in the central nervous system. This G-protein-coupled chemokine receptor appears to play a critical role in ensuring the necessary patterns of migration of granule cells in the cerebellar anlage.
In attempting to better understand the relationship between chemokines and their receptors, recent experiments to block the binding of HIV to the CXCR-4 chemokine receptor were carried out through the use of monoclonal antibodies or small molecules that appear to suggest a useful therapeutic strategy (Schols et al., J. Exp. Med. 186:1383-1388 (1997); Schols et al., Antiviral Research 35:147-156 (1997)). Small molecules, such as bicyclams, appear to specifically interfere with the CXCR-4 binding and not CCR-5 binding (Donzella et al., Nature Medicine, 4:72-77 (1998)). These experiments demonstrated interference with HIV entry and membrane fusion into the target cell in vitro. Additional experiments monitoring the calcium flux or Ca2+ mobilization assay demonstrated that a bicyclam also functioned as an antagonist to signal transduction resulting from the binding of stromal derived factor or SDF-1xcex1, the natural chemokine to CXCR-4.
U.S. Pat. Nos. 5,583,131, 5,698,546 and allowed copending U.S. application Ser. No. 08/659,500 disclose cyclic compounds that are active against HIV-1 and HIV-2 in in vitro tests. We have now discovered that these compounds exhibit anti-HIV activity due to their binding to the chemokine receptor 4 (CXCR-4 or Fusin receptor), expressed on the surface of certain cells of the immune system. This competitive binding thereby protects these target cells from infection by HIV which utilize the CXCR-4 receptor for entry. We have discovered that the disclosed compounds also antagonize the binding, signaling and chemotactic effects of the natural CXC-chemokine for CXCR-4, stromal cell-derived factor 1xcex1 (SDF-1xcex1). Herein, we further disclose novel compounds that demonstrate protective effects against HIV infection of target cells by inhibition of binding in vitro to the CC-5 receptor (CCR-5).
The present invention provides novel compounds, that demonstrate protective effects on target cells from HIV infection as well as demonstrate other biological activities related to the ability of these compounds to inhibit the binding by the natural ligand to its chemokine receptor.
Accordingly, the present invention provides a macrocyclic compound of formula I:
Vxe2x80x94CR1R2xe2x80x94Arxe2x80x94CR3R4xe2x80x94N(R5)xe2x80x94(CR6R7)xxe2x80x94R8xe2x80x83xe2x80x83(I)
wherein
V is a cyclic polyamine moiety having a total of 9 to 24 members and from 3 to 6 optionally substituted amine nitrogens spaced by two or more optionally substituted carbon atoms from each other, and which may optionally comprise a fused aromatic or heteroaromatic ring;
R1 to R7 may be the same or different and are independently selected from hydrogen or straight, branched or cyclic C1-6 alkyl;
R8 is a heterocyclic group, a substituted aromatic group, or a mercaptan group;
Ar is an aromatic or heteroaromatic ring each optionally substituted at single or multiple positions with electrons-donating or withdrawing groups;
x is 1 or 2;
and the acid addition salts and metal complexes thereof.
Preferably V is a 14- to 17 membered fused or unfused ring system, such as a cyclam system or a 4,7,10,17-tetraazabicyclo[13.3.1]heptadeca-1(17),13,15-triene system or a derivative thereof, and especially a cyclam system or derivative thereof. The moiety V may be substituted at C or N non-linking atoms, suitably by hydroxyl, alkoxy, thiol, thioalkyl or any other atom or group which does not adversely affect the activity or toxicity of the compounds but may reduce the basicity of the amines, for example halogen, nitro, carboxy, carboxyamido, sulphonic acid or phosphate. Suitably the fused aromatic or heteroaromatic ring is phenyl, pyridine, pyrimidine, pyrazine, imidazole or thiazole. Preferably, the fused aromatic or heteroaromatic ring is phenyl or pyridine.
Preferably R1 to R7 are each hydrogen.
Preferably R8 is selected from pyridine, pyrimidine, pyrazine, imidazole, thiophene, thiophenyl, aminobenzyl, piperidinyl, piperazinyl or a mercaptan group.
Preferably Ar is phenyl. Preferred substituents are alkyl, aryl, amino, alkoxy, hydroxy, halogen, carboxyl and carboxamido.
The invention also includes what may be termed as xe2x80x9cpro-drugxe2x80x9d, that is protected forms of the compounds, which release the compound after administration to a patient. For example, the compound may carry a protective groups which is split off by hydrolysis in body fluids e.g. in the bloodstream, thus releasing active compound or are oxidized or reduced in body fluids to release the compound. A discussion or pro-drugs may be found in xe2x80x9cSmith and Williams"" Introduction to the Principles of Drug Designxe2x80x9d, H. J. Smith, Wright, Second Edition, London 1988.
Acid addition salts, for example hydrochlorides, and non-toxic labile metal complexes of compounds of formula I are also active compounds according to the present invention. Non-toxic in the present tense has to be considered with reference to the prognosis for the infected patient without treatment. Copper and zinc complexes are preferred although other metals such as nickel may be considered, whereas less labile metals such as cobalt and rhodium are less preferred because of likely lower selectivity.
Compounds of formula I are novel. Accordingly, a further aspect of the invention provides a process for the preparation of a compound of formula I which comprises the following steps:
(i) nucleophilic attack by the cyclic polyamine V having a single unprotected amine nitrogen, all other amine nitrogen atoms being protected, on an excess of a compound of formula II
Yxe2x80x94CR1R2xe2x80x94Arxe2x80x94CR3R4xe2x80x94Yxe2x80x83xe2x80x83(II)
wherein R1 to R4 and Ar are as hereinbefore defined, and each Y is an active substituent which can be displaced by the unprotected nitrogen of polyamine V and is preferably selected from Br, Cl, I, methane sulphonate, 4-toluenesulphonate, trifluoromethane sulphonate.
It is well within the capabilities and knowledge of the skilled synthetic chemist to protect the amine nitrogens of cyclic polyamines, and it is preferred to use substitution by methanesulphonyl and/or toluenesulphonyl and/or diethoxyphosphoryl (see: Bridger et al, J. Med. Chem., 38:366-378 (1995); Bridger et al, U.S. Pat. No. 5,583,131 or Bridger et al, U.S. Pat. No. 5,698,546) and/or nitrobenzenesulfonyl (Fukuyama et al., Tetrahedron Letters 1995, 36, 6373-6374.
The protected polyamine V is firstly reacted with a 5- to 10-fold excess of a compound of formula II in a solvent such as acetonitrile or dimethylformamide, tetrahydrofuran or dioxane and in the presence of a base, for example sodium carbonate or potassium carbonate. The reaction generally proceeds at room temperature to elevated temperature to give a cyclic polyamine in which all amine nitrogens are protected. In general, a mixture of products will be obtained and we have found that the product can conveniently be purified by silica gel chromatography or crystallization.
Nucleophilic attack of a compound of formula III
R5NHxe2x80x94(CR6R7)xxe2x80x94R8xe2x80x83xe2x80x83(III)
wherein R5 to R8 and x are as hereinbefore defined on the product of the reaction described at (I) above, and subsequently de-protecting the amine nitrogens. The reaction with an excess of a compound of formula III is carried out under similar conditions to the reaction with the polyamine V.
The de-protection step is suitably carried out by re-fluxing the protected molecule in a mixture of aqueous HBr and acetic acid or concentrated sulphuric acid, or in the case of diethoxyphosphoryl in the presence of gaseous hydrogen chloride or gaseous hydrogen bromide in acetic acid; in the case of nitrobenzenesulfonyl deprotection, a mercaptan such as thiophenol or mercaptoacetic acid in the presence of a suitable base such as potassium carbonate, cesium carbonate, sodium hydroxide or lithium hydroxide in a solvent such as dimethylformamide, acetonitrile, tetrahydrofuran or dioxane is used. This reaction generally proceeds at room temperature to elevated temperatures to give a polyamine in which the nitrogens are deprotected. Alternatively, and accordingly, a further aspect of the invention provides a process for the preparation of compounds of Formula I which comprises the following steps:
(i) nucleophilic attack by the cyclic polyamine V having a single unprotected amine nitrogen, all other amine nitrogens being protected, with an excess of a compound of formula (IV)
Yxe2x80x94CR1R2xe2x80x94Arxe2x80x94CR3R4xe2x80x94N(R5)xe2x80x94(CR6R7)xxe2x80x94R8xe2x80x83xe2x80x83(IV)
Wherein R1 to R4 and x, R6 to R8 and Ar are as hereinbefore defined and Y is an active substituent which can be displaced by the unprotected nitrogen of cyclic polyamine V as hereinbefore defined. In this case, the intended substituent R5 is hydrogen but for convenience, the nitrogen is protected as a nitrobenzenesulfonyl or diethoxyphosphoryl group.
The protected polyamine V is first reacted with a compound of formula IV using similar conditions to the reactions with compounds of formula II and formula III as described above and the product of this reaction is subjected to deprotection of the amine nitrogens on the polyamine and at R5.
The deprotection steps were carried out as described above. For convenience, a sequential combination of these deprotection reactions may be used when both diethoxyphosphoryl and nitrobenzenesulfonyl groups are present.
The novel compounds further comprise a macrocyclic compound of general formula V:
V2xe2x80x94CR9R10xe2x80x94Ar2xe2x80x83xe2x80x83(V)
where V2 is a cyclic polyamine moiety having a total of 9 to 24 members and from 3 to 6 optionally substituted amine nitrogens spaced by two or more optionally substituted carbon atoms from each other, and which may optionally comprise a fused aromatic or heteroaromatic ring; where R9 and R10 may be the same or different and are independently selected from hydrogen or straight, branched or cyclic C1-6 alkyl; further, where Ar2 is an aromatic, fused aromatic, heterocyclic or fused heterocyclic ring each optionally substituted at single or multiple positions with electron-donating or withdrawing groups and/or aromatic and heterocyclic groups and their alkyl derivatives thereof; and the acid addition salts and metal complexes.
These novel compounds have demonstrated anti-HIV activity in an in vitro screen assay as presented in Table 1. These novel compounds have also demonstrated biological activity in inhibiting CXCR-4 specific monoclonal antibody (12G5) from binding to CXCR-4 on SUP-T1 cells by AMD compounds. These data are shown in Table 2 for AMD3100 (1,1xe2x80x2-[1,4-phenylenebis(methylene)]bis-1,4,8,11-tetraazacyclotetradecane tetrahydrochloride, AMD3465 (N-[1,4,8,11-tetraazacyclotetra-decanyl-1,4-phenylenebis(methylene)]-N-2-(aminomethyl)pyridine) and six new compounds: AMD 7049; AMD 7050; AMD 7051; AMD 7058; AMD 7059; and AMD 7063.
Data showing inhibition of the increased Ca2+ flux induced by SDF-1 in SUP-T1 cells (inhibition of signal transduction) by AMD compounds are shown in Table 3 for AMD3100, AMD3465 and compounds: AMD 7049; AMD 7050; AMD 7051; AMD 7058; AMD 7059; and AMD 7063.
Several novel compounds also inhibited infection of the cell line U87.CD4.CCR5 by the M-tropic HIV-1 strain BaL, which exclusively utilizes the CCR-5 co-receptor for entry. These data are shown in Table 4.
The experimental procedures for the mAb binding assay, the inhibition of Ca2+ flux, and inhibition of infection by the HIV-1 BaL strain in U87.CD4.CCR5 cells would be readily understood by the skilled artisan. For example, see: Schols et al., J. Exp. Med. 186:1383-1388 (1997); Schols et al., Antiviral Research 35:147-156 (1997); and Donzella et al., Nature Medicine, 4:72-77 (1998). Also, the characterization of the CXCR-4 specific monoclonal antibody 12G5 is taught by Hoxie et al., Cell, 87:745-756 (1996).
Citation of the above documents is not intended as an admission that any of the foregoing is pertinent prior art. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicants and does not constitute any admission as to the correctness of the dates or contents of these documents.
Having now generally described the invention, the same will be more readily understood through reference to the following examples which are provided by way of illustration, and are not intended to be limiting of the present invention, unless specified.
As mentioned above, the compounds of the invention have activity against viral infections, especially retrovirus infections and specifically HIV. Accordingly, a further aspect of the invention provides a compound of formula I or formula V for use in medicine. More specifically, there is provided the use of a compound of formula I or formula V in the manufacture of a medicament for the treatment of HIV-infected patients. In the alternative, there is provided a method of treating an HIV-infected patient comprising administering to said patient, a pharmaceutically effective amount of a compound of formula I or formula V. Although compounds of formula I or formula V could be administered as the raw material, it is preferable to present them in the form of a pharmaceutical composition comprising a compound of formula I or formula V as active ingredient in admixture with a pharmaceutically acceptable diluent or carrier and optionally one or more other therapeutic ingredients, such compositions providing a further aspect of the invention.
In all aspects of the invention, it is understood that meso forms, enantiomers and resolved optically active forms of the compounds of formula I or formula V are also included. Also, it is to be considered within the invention, compounds of formula I or formula V diluted with non-toxic or other active substances.